Method and system for encoding and transmitting high definition 3-d multimedia content

ABSTRACT

One particular implementation of the present invention may take the form of a method and system for encoding decoding 3-D multimedia content. In one example, visual content having a plurality of source frames may be processed to create a plurality of first and second type frames from each of the plurality of source frames. The plurality of first and second type frames may be arranged to create modified content, and generating a distinguishing signal for the visual content, which may distinguish the first type frame from the second type frame. In another examples, the present invention may take the form of a method decoding 3-D multimedia content encoded with at least content frames and null frames. The method may operate to receive the 3-D multimedia content, extract at least one content frame, at least one null frame, and display information. The method may further operate to reconstruct the content and null frames in a display-sequential manner using the display information to indicate the display order of the at least one content frame. In some examples, the method and system for encoding and decoding multimedia content may encode the multimedia content such that the at least one null frame may not be displayed by a display device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/651,320, entitled “Method and System for Encoding and TransmittingHigh Definition 3-D Multimedia Content,” filed Oct. 12, 2012, which is acontinuation of U.S. patent application Ser. No. 12/547,376, entitled“Method and System for Encoding and Transmitting High Definition 3-DMultimedia Content,” filed Aug. 25, 2009, now U.S. Pat. No. 8,289,374,which is incorporated by reference in its entirety herein.

FIELD OF THE INVENTION

Aspects of the present invention relate to display of 3-D multimediacontent. More particularly, aspects of the present invention involve asystem and method for encoding and transmitting high definition 3-Dcontent to a display device.

BACKGROUND

Three dimensional (3-D) imaging, or stereoscopy, is a technique used tocreate the illusion of depth in an image. In many cases, the 3-D effectof an image is created by providing a slightly different image of ascene to each eye of a viewer. The slightly different images may presenttwo perspectives of the same object, where the perspectives differ fromeach other in a manner similar to the perspectives that the viewer'seyes may naturally experience when directly viewing a three dimensionalscene. When the two images are viewed at the same time, the image isperceived as having depth.

Several methods exist to provide a 3-D effect to an image. An anaglyphimage may present the two images for each of the viewer's eyes indifferent colors, such as red and blue-green. To achieve the 3-D effect,the viewer wears glasses with color filter lenses that filter thecolor(s) so as to present only one of the images for each eye. Thus, theviewer's right eye receives the red image while the viewer's left eyereceives the blue-green image. When the left-eye image and the right-eyeimage are viewed at the same time, the viewer perceives a 3-D effect. Inanother example, left-eye and right-eye image are superimposed throughpolarizing filters such that one image is clockwise polarized and theother image is counter-clockwise polarized. The viewer wears glasseswith polarized lenses such that each eye receives only one of theimages. In a third example, the 3-D images are presented in atime-multiplexed fashion, such as alternating between images meant forthe viewer's right eye and the viewer's left eye. The viewer wearsglasses that shutter between the viewer's eyes, allowing the right eyeto receive the right eye image and the left eye to receive the left eyeimage.

To transmit 3-D or “stereo” multimedia content (such as 3-D video orfilm), both left-eye and right-eye images are sent to a display devicein a manner that allows the left-eye and right-eye images to beseparately presented to the user's left eye and right eye, respectively.Conventional digital interfaces and transmission standards are notdesigned to support 3-D content that involves transmitting twice as manyvideo frames as non-stereo video. This is a particular problem for highdefinition video which requires significantly more data for each frameas compared to standard definition video. Techniques have beendeveloped, however, to squeeze a left-eye frame and a right-eye frameinto the space of a single video frame allowing a stereo video to becommunicated using conventional digital interfaces and transmissionstandards. For example, one method transmits the images for both eyes ofa 3-D image by fitting the images for the right and left eye into asingle frame, in a side-by-side arrangement (e.g., dividing theconventional frame into a left half and right half) or over-underarrangement (e.g., dividing the conventional frame into an upper halfand a lower half). In another example, anamorphic squeeze techniques areused to squeeze each of the left-eye and the right-eye images into thesmaller space for transmission as a single frame. The two images maythen be separated, expanded and presented to the viewer in a mannerconsistent with 3-D techniques by the display device. Another methodinvolves transmitting both images in a checkerboard fashion in a singleframe. Thus, the pixels of the images for each eye are interleaved intoa single frame on a pixel-level basis. These methods may provide thedata for the two images needed for a single 3-D image at the same rateas 2-D images may be transmitted. However, because two images are beingpresented in a single frame, the resolution of each image is less thanif each frame contained a single image. Thus, the images provided inthese schemes may not meet the high resolution requirements of highdefinition video.

High definition video generally refers to multimedia content presentedin a display resolution of 720 p or higher. A resolution of 720 pindicates that each frame of the image presented has a verticalresolution of 720 pixel lines and that each pixel line of the image isrefreshed when the image is updated. A high definition television modespecified as 720 p typically has an aspect ratio of 16:9 and, therefore,has a horizontal resolution of 1280 pixels, resulting in 921,600(720×1280) pixels in each frame. Further, high definition video is oftentransmitted at 60 frames per second, meaning that the entire image isupdated 60 times per second in progressive modes. Video with higherresolutions and frame rates may also satisfy the high definitionstandard.

Since 3-D content is often transmitted by squeezing or interleaving theimages for the left and right eye into a single frame, each of theleft-eye and right-eye images can use only half of the pixels availablein the frame. For example, a 720 p frame can be vertically divided butsuch a division allows only 360 vertical lines for each image. Whilesome methods exist to improve the appearance of the squeezed or combinedimages, the transmitted images may no longer satisfy the qualityexpectations of a high definition image. Thus, what is needed, amongother things, is a method and system for encoding and transmitting 3-Dmultimedia content that meets the resolution expectations of highdefinition video and is at the same time compatible with existingdigital interfaces and transmission standards.

SUMMARY

One implementation may take the form of a method for encoding visualcontent. The method may comprise the operation of receiving by aprocessing element the visual content. The visual content may comprise aplurality of source frames. The method may also comprise the operationof creating by the processing element, for each source frame in theplurality of source frames, a first type frame and a second type frame.The first type frame and second type frame may utilize a full resolutionof a display device for displaying the visual content. The method mayfurther comprise the operation of arranging by the processing elementthe plurality of first type frames and second type frames to definemodified content. The method may also comprise the operation ofgenerating by the processing element a distinguishing signal for thevisual content. The distinguishing signal may distinguish the first typeframe from the second type frame.

Another implementation may take the form of a method for decodingthree-dimensional (3-D) multimedia content. The method may comprise theoperation of receiving by a processing element the 3-D multimediacontent. The 3-D multimedia content may be encoded and comprise at leastcontent frames and null frames. The method may further comprise theoperation of extracting by the processing element the encoded 3-Dmultimedia content to obtain at least one content frame, at least onenull frame, and display information corresponding to the at least onecontent frame and the at least one null frame. The method may alsocomprise the operation of using the display information, reconstructingby the processing element the at least one content frames and the nullframes in a display-sequential manner to indicate the display order ofthe at least one content frame.

Another implementation may take the form of a method for decodingencoded content. The method may comprise the operation of receiving by aprocessing element the encoded frames. The encoded frames may compriseat least one content frame and at least one null frame. The method mayalso comprise the operation of detecting by the processing element asynchronization signal corresponding to the encoded frames. The methodmay further comprise the operation of and compiling by the processingelement the encoded frames into a frame-sequential stream of framesaccording to the detected synchronization signal, such that the at leastone null frame is not displayed when the frame-sequential stream offrames is displayed.

Another implementation may take the form of a system comprising adisplay device and a decoder. The system may comprise a display devicecapable of displaying 3-D multimedia content. The system may alsocomprise a decoder configured to operate to extract an encoded stream offrames having a first image type, a second image type, and at least onenull image from a 3-D content source. The decoder may further operate toobtain synchronization information from the encoded stream of frames andgenerate a frame-sequential stream of frames for the first image type,the second image type, and the at least one null image based on thesynchronization information. The decoder may also be configured tooperate to transmit the frame-sequential stream of frames to a displaydevice. The display device may be configured to discard the null imageswhen the frame-sequential stream of frames is displayed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a system for transmitting highdefinition 3-D content to a display device.

FIG. 2 is a diagram illustrating a system for transmitting a highdefinition 3-D content to a source device.

FIG. 3 is a diagram illustrating a first embodiment of a series offrames containing 3-D content and null frames.

FIG. 4 is a diagram illustrating a second embodiment of a series offrames containing 3-D content and null frames.

FIG. 5 is a diagram illustrating pixels of a 3-D multimedia frameincluding an in-line synchronization signal contained within the firstline of pixels.

FIG. 6 is a block diagram illustrating a system for encoding highdefinition 3-D multimedia content to a computer-readable medium.

FIG. 7 is a flowchart of a method for encoding high definition 3-Dcontent to a computer-readable medium.

FIG. 8 is a high-level block diagram illustrating a particular systemfor providing high definition 3-D multimedia content.

DETAILED DESCRIPTION

Implementations of the present invention involve methods and systems forencoding and/or transmitting high definition 3-D multimedia content,such as 3-D video. The frames of the 3-D video may be encoded ortransmitted in a frame-sequential fashion, with some image framesintended for the viewer's right eye and other frames intended for theviewer's left eye. To account for the addition of frames intended foreach eye of the viewer, one embodiment may encode and/or transmit theframes at a frame rate about twice that of a source content or higher.For example, a 30 frame per second 3-D video may be encoded andtransmitted at 60 frames per second to account for the separation of theright-eye images and the left-eye images into separate frames. Further,in some implementations, null frames may be inserted into thetransmitted or encoded frame stream to accommodate a mismatch betweenthe increased frame rate in accordance with the present invention and anindustry standard frame rate. In such an implementation, the null framesmay be recognized and discarded by downstream image processing and/ordisplay devices. Such downstream image processing devices may include,but are not limited to, a digital video disc (DVD) player, a digitalvideo recorder (DVR), set-top box (STB) for a satellite or digital cablesystem, a television, and a personal computer, and such.

In some implementations, a synchronization signal is transmitted in-bandor out-of-band to downstream image processing and/or display devices.The synchronization signal instructs the display device on how todistinguish between left-eye and right-eye frames in the frame sequencedstream. Such a synchronization signal may describe the sequence at whicheach transmitted frame is to be displayed to the viewer. Thesynchronization signal may be presented to the display device embeddedwithin the content frames (i.e., “in-band”) of the multimedia contentor, in cases including null frames, embedded within the null framesthemselves. Synchronization signals may also be provided out-of-band,such as on a high definition multimedia interface (HDMI) cable or othercommunication channel to the display device.

In one arrangement, the sequence of image frames and null frames may actas a synchronization signal. In such an arrangement, a display device orother downstream image processing device is configured to automaticallydetermine a cadence to the transmitted frames upon receipt of aninitiation signal and use the determined cadence to distinguish andseparately display left-eye and right-eye images to a viewer.

FIG. 1 is a diagram illustrating a system for transmitting highdefinition 3-D content between a source 110 and a display 120. Theembodiment of FIG. 1 may provide the 3-D content at a resolution thatsatisfies a high definition video standard by transmitting right-eyeframes 180 and left-eye frames 190 in a frame-sequential fashion. Theframes 140 may be transmitted to a display device 120 such that thedisplay device 120 presents the frames 140 to the user utilizing atechnique to provide the images with a 3-D effect. For convenience, thecontent is portrayed as a series of frames 140 transmitted from thesource 110 to the display 120 in FIG. 1.

Generally, video content may be transmitted by a source device 110 to adisplay device 120 for display to the viewer. The source device 110 maytake many forms, including but not limited to, a Blu-ray Disk®compatible optical disc player, a laptop computer, a personal computer,a set-top box (STB) of a satellite or digital television system and avideo game console. Any device that may provide high definition contentthrough an electrical, wireless or optical connection, such as an I/Oport, may be a source device 110 and may be used with the embodiments asset forth herein.

In some embodiments, a computer readable data storage medium 130 may beassociated with the source device 110 to store the high definition 3-Dcontent. The source device 110 may access the storage medium 130 toretrieve the 3-D content and transmit the content to the display device120. The data storage medium 130 may take many forms, including but notlimited to, an optical disc (such as a Blu-ray Disk® compatible opticalmedia); magnetic storage medium; magneto-optical storage medium; readonly memory (ROM); random access memory (RAM); or other types oftangible medium suitable for storing electronic data. Generally, anytangible computer-readable medium capable of storing high definitioncontent may be used with the embodiments described herein and/or storevideo encoded pursuant to techniques described herein. In one example,the source device 110 is a Blu-ray Disk® compatible player. The 3-Dvideo content is stored on optical disks such that the player retrievesthe content from the disk. Upon retrieval, the player transmits frames140 to a display device 120, such as a television, to display thecontent to a viewer.

The display device 120 may be any device that may access frames 140 fromthe frame buffer 150 and present the accessed frames 140 to a viewer.Examples of display devices 120 include, but are not limited to, aliquid crystal display (LCD) or plasma television, a cathode-ray tube(CRT) television, a computer monitor and various types of projectionarrangements. To receive the frames 140, the display device 120 mayinclude an interface port that may receive the frames 140 from thesource device 110 for display and storage in the frame buffer 150. Theinterface port may be any port that supports a frame transfer rate of atleast 2× the frame rate of the content. Examples of interface portsinclude those ports conforming to industry standard interfacespecifications, such as HDMI, Digital Visual Interface (DVI),DisplayPort, etc.

In another embodiment, depicted in FIG. 2, the source device 110 may bea STB 210 associated with a distribution system 200, such as a cable,satellite, broadcast, network or other available digital distributionsystem. In the example of a satellite distribution system 200, thecontent is transmitted to the STB from a provider, such as a headend 250of the distribution system 200. The headend 250 transmits the content tothe STB 210 through a satellite 240 to a dish antenna 230 electricallyconnected to the STB 210. Alternatively, the headend 250 may transmitthe content directly to the STB 210 through a dedicated cable, such asin a digital cable example. In other embodiments, the content may beprovided to the source device 110 from a server through a networkconnection, such as over the internet.

Returning to FIG. 1, once the high definition content is received by thesource device 110, the content is transmitted to a display device 120that displays the content to a viewer. To transmit the content, thesource 110 may be connected with the display device 120 through anelectrical, wireless or optical connection. For example, the content maybe provided to the display device via a high definition multimediainterface (HDMI) cable. Generally, any communication channel thattransfers the data of each frame 140 of the content at a rate sufficientto meet current transmission standards or faster may be used to transmitthe content to the display. The video content is transmitted in frames140 containing the pixels of each discrete image, which when shownconsecutively provide moving video. The received frames 140 may then beplaced into a frame buffer 150 associated with the display device 120for access by the display device 120. Frame buffer 150 comprises acomputer-readable addressable memory, such as a dual-ported randomaccess memory (RAM). The frame buffer 150 should have sufficientcapacity and bandwidth to receive, store and forward at least two frames(one left-eye frame 190 and one right-eye frame 180) at anindustry-standard frame rate or higher. The frame buffer can be accessedby display 120 while also loading frames 140 from the frame buffer 150input such that the frames can be displayed without a perceivable delaywhen presented to the viewer. To display the content, the display device120 retrieves the frames 140 from the frame buffer 150 and displays theframes 140 at the correct time and in the correct sequence. Displayingthe sequence of frames 140 then appears as a motion video. For example,film is generally presented at 24 frames per second (fps) and televisionand video are generally presented at 30 fps.

To present the continuous motion effect for 3-D content, the frame rateof the 3-D content may be increased to at least two times (2×) the framerate of the content source to include both the frames for the viewer'sright-eye and the viewer's left-eye. For example, the frame rate fornon-stereo video is generally presented at 30 fps. To transmit both theright-eye image and left-eye image for the 3-D content, the separate eyeimages may be encoded and/or transmitted to the display device 120 indifferent frames. One frame may include a left-eye image while anotherframe may include the corresponding right-eye image. The separatedframes may then be encoded and/or transmitted at a rate of 60 fps, witha sequence of 30 frames containing the images for the viewer's right eyeand a sequence of 30 frames containing the images for the viewer's lefteye for every second of the content. Similarly, 3-D film content isprovided at a rate of 48 fps, with 24 frames for the viewer's right eyeand 24 frames for the viewer's left eye.

As shown in FIG. 1, the content transmitted to the display device 120 isshown as a series of frames 140. However, the display device 120 may notnecessarily receive all of the data corresponding with a single frame140 from the source device 110 at once. Rather, the source device 110may provide a stream of digital data to the display device 120 thatrepresents the pixels of each frame 140 of the content. Such is thecase, for example, if the content is compressed or encrypted. Thedisplay device 120 or other downstream image processing device may thendecompress, decrypt or otherwise decode the incoming data, build orcompile each frame 140 of the image to be displayed from the provideddata and store the compiled frames 140 in the buffer 150 for display atthe appropriate time. Thus, the content may be transmitted to thedisplay device 120 in any manner that enables display device 120 toaccess and/or reconstruct frames 140 at a frame rate that is a leasttwice the frame rate of the content source.

In one implementation, the frames 140 are transmitted to the displaydevice 120 in a frame-sequential fashion, such that the content frames140 are provided in a sequence of left-eye and right-eye frames that isrecognized by the display device 120 for proper display to a viewer. Inthe embodiment depicted in FIG. 1, for example, right-eye frames 180 andleft-eye frames 190 are transmitted in an alternating, interleaved,frame-sequential fashion. Thus, a single left-eye frame 160 containingan image intended for the viewers left eye is transmitted, followed by asingle right-eye frame 170 containing an image intended for the viewersright eye. This pattern of transmitting the frames of the content may berepeated, alternating left-eye frames (“L”) 190 and right-eye frames(“R”) 180, while the source device 110 is providing the content to thedisplay device 120. Alternatively, the frames may be transmitted to thedisplay device 120 such that two right-eye frames 180 are transmitted tothe display 120, followed by two left-eye frames 190, and so on. In yetanother example, several right-eye frames (e.g., 24 or 30 right eyeframes) may be followed by several left-eye frames (e.g., 24 or 30 righteye frames). Generally, the frames 140 may transmitted to the display120 in any order, as long as the display device 120 may place the frames140 in the proper order for presentation to the viewer without aperceivable delay in the presentation of the content to the viewer.

To maintain the desired frame rate for the 3-D content, the frames 140are transmitted at a frame rate of at least two times (2×) compared tothe frame rate of the content source. For example, in a conventionalarrangement, video is often rendered at 30 fps, with each framecontaining resolution-compromised (e.g., compressed, squeezed or thelike) versions of both the left-eye image and the right-eye image. Inaccordance with aspects of the present invention, the left-eye and righteye images are transmitted in different frames 140 such that each imagehas the full resolution available in the entire frame 140. Thus, each3-D image comprising a left-eye image and a right-eye image istransmitted in two frames 140, a single frame 160 for the left-eye imageand a single frame 170 for the right-eye image. Therefore, 3-D videocontent may be encoded and/or transmitted at a rate of 60 fps.Similarly, 3-D film content is provided at a rate of 48 fps, which istwice the frame rate (24 fps) of conventional film content. Further, bytransmitting the frames at a higher rate, the high definition resolutionof each image is maintained since there is no need to compress orsqueeze the right-eye and left-eye images for transmission.

Broadcast and electrical interface standards exist for transmitting highdefinition content at 60 fps with a resolution of 720 p. Conventionalfilm content at 24 fps and video content at 30 fps require less than orequal to half the bandwidth available in the existing transmissioninfrastructure and electrical interface standards. Aspects of thepresent invention take advantage of the available bandwidth to transmitat least twice as many frames as compared to the conventional content,allocating substantially half of the frames for left-eye and half forright-eye. In this manner, aspects of the present invention enable 3-Dmultimedia to be transmitted as high definition without the loss ofresolution to the images.

For 3-D video content, which is shown at a rate of 30 fps, transmittingalternating left eye and right eye frames requires 60 fps and thus fitswithin the 60 fps available for high definition video. However, 3-Dcinema content, provided at 24 fps requires 48 fps to handle left-eyeand right-eye frames and so does not fit neatly within the 60 fps rate.In the case of film content, additional frames are used inimplementations of the present invention to adapt the 48 fps rate intothe 60 fps transmission rate of high definition video transmission andinterface conventions.

FIG. 3 is a diagram illustrating a series of frames including 3-Dcontent frames 310 and null frames 320 encoded pursuant to aspects ofthe invention. This embodiment illustrates how high definition 3-Dcinema multimedia content may be transmitted using a 60 fps transmissionrate. A greater or lesser number of null frames 320 may be providedwithin the transmission stream 300 so as to adapt to other transmissionrates and/or other source content frames rates. For convenience, thecontent is portrayed as a stream of frames 300 in FIG. 3. The stream 300includes content frames 310 (including both left-eye image frames (“L”)and right-eye image frames (“R”) and null frames 320, shown in black.

3-D cinema content with a source frame rate of 24 fps is produced withseparate left-eye and right-eye frames at a rate of 48 fps. In oneembodiment, the right eye frames and left eye frames are transmitted ina frame-sequential fashion, alternating between left and right frames.However, for 3-D cinema content, the content frames 310 including theimages of the content only require 48 fps of the 60 fps capacity,leaving 12 fps in the transmission stream 300 to account for. Thus, nullframes 320 are included within the stream 300 to occupy the 12 fpscapacity that is not used to transmit content frames 310.

The null frames 320 included in the stream of frames 300 may include anyinformation, image, pattern or other indicia recognized by the displaydevice 120 as a null frame 320. Generally, the display device 120 isconfigured to identify the null frames 320 within the stream of frames300 either implicitly (e.g. a frame that does not bear characteristicsof a content frame 310 is deemed to be a null frame 320) or explicitly(e.g., indicia within a frame identifies the frame as a null frame 320).For example, the null frames 320 may include only black pixels thatsignal the display device 120 to ignore the null frames 320 or otherwisehandle the frames as null frames 320. The occurrence of a null frame 320may also signal display device 120 that the next subsequent frame is aleft-eye frame 190 or a right-eye frame 180, for example. In thismanner, the null frames 320 can be used to convey signaling informationthat can be used by display device 120 to properly sequence playback.

Null frames 320 are inserted into the frame stream 300 as every fifthframe, in one possible arrangement. Thus, four content frames 310 may betransmitted for each null frame 320, alternating between left-eye imagesand right-eye images in the embodiment illustrated in FIG. 3. However,the null frames 320 of the frame stream 300 may be placed anywherewithin the frame stream 300. For example, in the embodiment of FIG. 4null frames 420 are placed after ten content frames 410 are transmitted.Further, to ensure that twelve null frames are included in the stream400 (to transmit 48 frames in a 60 fps transmission rate), twoconsecutive null frames 420 may be included in the stream 400.

In conventional 2D content, every frame is essentially similar to everyother frame in that there is no left-eye or right-eye separation at thedisplay device 120. When displaying 3D content it is important to ensurethat the display remains able to properly pair left-eye 190 and righteye images 180 and to accurately determine whether a particular image isa left-eye image or a right-eye image. To assist the display device 120in presenting the content correctly, a synchronization signal typicallyprovided to the display device 120 to instruct the display device 120 asto which frames 140 are to be presented and in which order the imagesare to be displayed to create the 3-D effect.

FIG. 5 is one embodiment for providing a synchronization signal byincluding an in-band synchronization signal contained within a frame500. FIG. 5 illustrates several pixels of a frame 500, such as thepixels of the upper rightmost corner of the frame image. Signal pixels520 designated by “S” represent synchronization pixels embedded withinthe frame 500 while pixels designated by “P” represent data pixels.Frame 500 may be a content frame (310, 410) or a null frame (320, 420).

In this example, the synchronization signal takes the form of dataembedded within a line of pixels 510 of the frame 500, such as the firstline 510 of the frame 500. Alternatively, the synchronization signal maybe embedded within any pixels of the frames of the content in a mannerthat allows display device 120 to identify the pixels used for thesynchronization signal.

The synchronization signal is read by the display device 120 from theframe 500 when the frame 500 is received and processed.

As shown in FIG. 5, the content frame 500 is composed of a set ofpixels. For example, in one embodiment the frame 500 may be 1280 pixelswide and 720 pixels tall. Each pixel of the frame 500 may include asmall part of the overall image presented by the frame 500. However, thepixels of each frame 500 may also be utilized to transmit asynchronization signal to the display device 120 by altering the colorof the signal pixels 520 representing the synchronization signal withinthe frame 500. For example, signal pixels 520 may be all black to signalthe display device 120 that the frame is a left-eye frame. Generally,the signal pixels 520 may be any color that signals to the displaydevice 120 the proper sequence or type of the frame 500. Further, thesynchronization signal pixels 520 may be any number of the pixels or inany location within the frame 500. For example, a single black pixel inthe upper right corner of the frame 500 may indicate a left-eye imageframe while a single white pixel in the same position may indicate aright-eye image. In this manner, the 3-D content provider has controlover the sequence of the content by controlling the color of the signalpixels 520.

Upon receipt, the synchronization signal provides an indication enablingthe display device 120 to determine whether a particular frame 500 orgroup of frames 140 are left-eye or right-eye frames. For example, thesynchronization signal may inform the display device 120 that the frame500 is intended for the left eye of the viewer. The display device 120then processes the frame 500 accordingly, such as placing the frame 500in the proper order in the frame stream being displayed. In otherembodiments, the synchronization signal enables the display device 120to pair a particular left-eye frame 160 with a matching right-eye frame170 to create the 3-D image. Generally, the synchronization signal mayinclude any information that may assist the display device 120 incompiling and displaying the 3-D content.

In the embodiment shown in FIG. 5, the synchronization signal is afour-pixel signal contained within the first line of pixels 510 of theimage frame 500. Thus, pixels 1-4 of the first line of pixels 510 of theframe 500 contain the signal pixels 520 of the synchronization signal.However, the synchronization signal pixels 520 are not required to betransmitted on the first line of pixels 510 of the frame 500. Rather,the synchronization signal pixels 520 may be included anywhere withinthe frame 500. Other embodiments may instruct the display device 120 tolook in a particular area within the frame 500 to locate and read thesynchronization signal pixels 520.

The display device 120 is configured to recognize when synchronizationsignal pixels 520 are embedded within the frame 500 and adjust thedisplay of the frame 500 accordingly. Further, the display device 120may be configured to not present the synchronization signal pixels 520to the viewer. Thus, in the example where the synchronization signalpixels 520 are located in the first line of pixels 510 of the frame 500,the display device 120 may be configured to not display the first lineof pixels 510 to the viewer. Instead, the display device 120 may convertthe first line of pixels 510 into an all black line for presentation tothe viewer or may disregard the line altogether. In this manner, asynchronization signal may be embedded within the transmitted frames 140that may instruct the display device 120 on how to compile the frames140 and, in some cases, the sequence in which the frames 140 should bedisplayed.

One disadvantage to including the synchronization signal in-band is thatthe viewer may detect or otherwise recognize the altered pixels of theimage. Thus, other embodiments may provide the synchronization signal tothe display device 120 without embedding the signal within the contentframes 140 of the content. In such embodiments, the synchronizationsignal may be provided to the display device 120 out-of-band over anexisting broadcast/interface specification. For example, thesynchronization signal may be provided to the display device 120 via anHDMI cable or similar interface. Generally, any communication channelmay be used to transmit the synchronization signal to the display,including wireless channels or coaxial cable. The synchronization signalmay be a single bit or several bits transmitted to the display device120 over the out-of-band interface to indicate the sequence and/or typeof frame being transmitted. The synchronization signal may betransmitted in an allowed space within the specification of the standardinterface, such as in a header within the information being transmittedover the interface. The display device 120 may then interpret andprocess the synchronization signal in a similar manner as describedabove.

It is not required that a synchronization signal be provided to thedisplay 120 for every transmitted frame. Rather, a synchronizationsignal may be provided to the display device 120 to set a cadence forthe incoming frames 140. For example, the display device 120 may beconfigured to recognize a left eye or right eye designation for theincoming frames 140 based on a synchronization signal that begins thecadence. Null frames (320, 420) are inserted into the transmitted framestream 300 in some embodiments. In the embodiments shown in FIG. 3 witha null frame 320 after every four content frames 310, the display device120 may be configured to recognize a left eye designation for the frame310 that immediately follows the null frame 320 and alternatedesignations for every frame 310 that follows until another null frame320 arrives. Thus, the display device 120 may then recognize a right eyedesignation to the next frame and continue alternating between a lefteye designation and right eye designation until the next null frame 320is detected. The display device 120 may also be configured to recognizea right eye designation for the frame 310 following the null frame 320and alternate with a left eye designation. However, in this embodiment,the null frames 320 of the frame stream 300 would likely be set up insuch a manner that the frames 310 that follow the null frames 320 wouldalways be intended for the same eye and thus receive the samedesignation. Generally, however, the display device 120 may recognizeany arbitrary pattern of left-eye and right-eye images that follows anull frame 320.

In a similar embodiment, the null frames 320 themselves may carry thesynchronization signal information for the frame 310 that follows thenull frame 320. In this example, the display device 120 may receive andrecognize a null frame 320 as described above. However, in this example,the null frame 320 may include a synchronization signal to instruct thedisplay or initiate a cadence. The synchronization signal may instructthe display device 120 to recognize a left-eye or right-eye designationfor the frame 310 following the null frame 320. Further, thesynchronization signal may instruct the display device 120 to alternatebetween left and right designations as described above on all incomingframes 310 until the next null frame 320 is received.

FIG. 6 is a block diagram illustrating a system for encoding highdefinition 3-D multimedia content to a computer-readable medium. Thesystem may include a telecine or similar apparatus to convert and encode3-D multimedia content from film or video onto a computer-readablemedium.

The system of FIG. 6 may include an encoder 630 that may be configuredto encode a stream of frames 620 from a 3-D source 610 to acomputer-readable medium 650. In one embodiment, the 3-D source 610 maybe a 3-D film or video involving multiple frames 620. The frames 620 maybe structured and presented to a viewer as described above to create a3-D image or series of 3-D images. In other embodiments, the 3-D contentis a digital data file containing information representing the frames620 of the multimedia source 610. Generally, any source involving aseries of frames may be used with the embodiment. The frames 620 of thesource 610 may be transmitted to the encoder 630 for encoding andstorage on a memory medium 650.

The encoder 630 may receive the frames 620 and encode the 3-D content ina similar manner as described above with reference to FIGS. 1-4. Theframes 620 may be encoded in an frame-sequential fashion 640,alternating between the left-eye frame and a right-eye frame. Further,the frames 620 of the content may be encoded to provide a particularframe rate to the content, such as 60 fps. For sources with frame ratesbelow 30 fps, the encoder 630 may insert several null frames into theframe-sequential frames 640 to ensure that the content is encoded at aparticular frame rate.

To insert the null frames into the frame stream 640 of the content, theencoder 630 may ascertain the frame rate of the source content 610. Ifthe encoder 630 determines that the frame rate of the source 610 is lessthan 30 fps, the encoder 630 inserts null frames into the frame stream640 of the content to provide a 60 fps frame rate to the encoder 630,including the added null frames. For example, a typical frame rate of3-D film is 24 fps which results in 48 fps when left-eye and right-eyeframes are transmitted separately in accordance with the presentinvention. A source 610 rendered at 24 fps may include 12 null frames toprovide a 60 fps frame rate of the content (48 frames of content and 12null frames). In this manner, 3-D content may be encoded at a frame rateand resolution that satisfies broadcast interface standards.

The encoder 630 may also include the synchronization signal into theencoding of the content 610. The synchronization signal may be encodedwithin each frame of the multimedia content, within the null frames ofthe frame stream 640 or provided out-of-band to the display, such as anavailable HDMI interface.

Once encoded, the high definition 3-D content may be recorded on acomputer-readable medium or otherwise distributed. The memory medium 650may take many forms, including but not limited to, an optical disc (suchas a Blu-ray Disk® compatible optical disc); magnetic storage medium;magneto-optical storage medium; read only memory (ROM); random accessmemory (RAM); external hard drive; flash memory or other types of mediumsuitable for storing electronic data.

FIG. 7 is a flowchart of a method for encoding high definition 3-Dcontent to a computer-readable medium in accordance with the presentinvention. The method may be practiced by the encoder 630 of FIG. 6 or asimilar device to encode 3-D content to a computer-readable medium orotherwise distribute the 3-D content.

In operation 710, the frame rate of a 3-D multimedia source isdetermined, typically because the source is provided with an indicationof the frame rate used by the content creator. Once the frame rate ofthe 3-D source is determined, the encoder ascertains which of the imagesof the 3-D content are those images intended to be viewed by the lefteye of the viewer and the images intended to be viewed by the right eyeof the viewer in operation 720.

In operation 730, null frames may be inserted into the frame streamencoded in operation 730. As explained in more detail above, the nullframes may be used to increase the frame rate of the encoded content to70 fps. The null frames may be inserted into the stream as desired toensure the 70 fps frame rate.

A synchronization signal may be encoded with the frame stream inoperation 740. The synchronization signal may be used to instruct adisplay device on the manner in which the frames of the content are tobe presented. The synchronization signal may be encoded within eachframe of the content, within the null frames of the frame streaminserted in operation 730 or provided out-of-band on a separate input tothe display.

It should be noted that the flowchart of FIG. 7 is illustrative only.Alternative embodiments of the present invention may add operations,omit operations, or change the order of operations without affecting thespirit and scope of the present invention.

FIG. 8 is a high-level block diagram illustrating a particular systemfor providing high definition 3-D multimedia content in accordance withthe present invention. In this particular embodiment, the 3-D content isencoded and stored on Blu-ray Disk® 810. The disk is encoded to includedigital information representing the image frames of the 3-D content,including the left-eye and right-eye frames for each image of thecontent. The information stored on the disk 810 is accessed and read bythe Blu-ray Disk® player 820 and transmitted to a decoder device 830.

Blu-ray Disks® 810 generally provide encoded content. Encodingrepresents a difference in the formats that are typically used forstoring or transmitting multimedia content and the formats used forintermediate processing of the multimedia content. The decoder 830translates between the storage and intermediate formats. For example,stored MPEG content is both compressed and encrypted. Prior to beingplayed at an output device, the stored MPEG content is decrypted anduncompressed by a decoder 830. The decoder 830 may comprise hardware,software, or some combination of hardware and software. Further, decoder830 may be integrated within the Blu-ray Disk® Player 820, may be astand-alone device, or may be integrated in the output device or otherdownstream image processing device.

Once decoded, the content is transmitted to a high definition television(HDTV) 840 over a suitable cable or other electrical connection fordisplay to a viewer. For example, the content may be transmitted to theHDTV 840 over a HDMI cable. Generally, the HDTV 840 is capable ofdisplaying the high definition quality content (i.e., a displayresolution of 720 p or higher). Once the content is received, the HDTV840 presents the content to the viewer. In the example, shown, the HDTV840 includes a video display 850 for presenting the frames of thecontent and speakers 870 to provide the sound of the content. In thismanner, the 3-D content stored on the Blu-ray Disk® 810 is presented tothe viewer for the viewer's entertainment.

The foregoing merely illustrates the principles of the invention.Various modifications and alterations to the described embodiments willbe apparent to those skilled in the art in view of the teachings herein.It will thus be appreciated that those skilled in the art will be ableto devise numerous systems, arrangements and methods which, although notexplicitly shown or described herein, embody the principles of theinvention and are thus within the spirit and scope of the presentinvention. From the above description and drawings, it will beunderstood by those of ordinary skill in the art that the particularembodiments shown and described are for purposes of illustrations onlyand are not intended to limit the scope of the present invention.References to details of particular embodiments are not intended tolimit the scope of the invention.

1. A method for encoding visual content for at least one of transmissionor display, the method comprising: receiving by a processing element thevisual content comprising a plurality of source frames; creating by theprocessing element for each source frame in the plurality of sourceframes a first type frame and a second type frame, wherein each of thefirst type frame and the second type frame utilize a full resolution ofa display device for displaying the visual content; arranging by theprocessing element the plurality of first type frames and second typeframes to define a modified content; and generating by the processingelement a distinguishing signal for the visual content, wherein thedistinguishing signal distinguishes the first type frame from the secondtype frame.
 2. The method of claim 1, wherein the distinguishing signaldetermines a display order of the first type frame and second typeframe.
 3. The method of claim 1, wherein the distinguishing signal isembedded in the modified content.
 4. The method of claim 1, wherein thedistinguishing signal is independent of the modified content.
 5. Themethod of claim 1, wherein the first type frame and second type frameeach comprise a plurality of pixels and the distinguishing signalcomprises a predetermined pixel pattern embedded in at least one of thefirst type frame and the second type frame.
 6. The method of claim 1,further comprising: determining by the processing element whether aframe rate of the modified content satisfies a standard frame rate; andwhen the frame is below the standard rate, increasing the frame rate tothe standard frame.
 7. The method of claim 6, wherein increasing theframe rate to the standard frame rate comprises inserting one or morenull frames into the modified content.
 8. The method claim of claim 7,wherein the distinguishing signal is included with the null frames. 9.The method claim of claim 7, wherein the visual content isthree-dimensional (3-D) visual content and wherein the first type frameis a left-eye frame and the second type frame is a right-eye frame. 10.A method for decoding three-dimensional (3-D) multimedia content,comprising: receiving by a processing element the 3-D multimediacontent, the 3-D multimedia content being encoded and comprising atleast content frames and null frames; extracting by the processingelement the encoded 3-D multimedia content to obtain at least onecontent frame, at least one null frame, and display informationcorresponding to the at least one content frame and the at least onenull frame; using the display information, reconstructing by theprocessing element the at least one content frames and the null framesin a display-sequential manner to indicate the display order of the atleast one content frame.
 11. The method of claim 10, wherein a framerate of the content frames is less than a standard frame rate; and aframe rate of the reconstructed content frames and null frames is equalto the standard frame rate.
 12. The method of claim 10, wherein the atleast one content frame comprises a first image type and a second imagetype.
 13. The method of claim 12, wherein the first image typecorresponds to one of a left-eye image and a right-eye image, and thesecond image type corresponds to the other of a left-eye image and aright-eye image.
 14. The method of claim 10, wherein the encoded 3-Dmultimedia content is one of compressed content, encrypted content, orcompressed and encrypted content.
 15. The method of claim 10, whereinthe reconstructing further comprises embedding the display informationin the display-sequential 3-D multimedia content.
 16. The method ofclaim 15, wherein the null frames include the display information. 17.The method of claim 15, wherein the at least one content frame comprisesa plurality of pixels and the display information comprises apredetermined pattern of pixels embedded in the at least one contentframe.
 18. A method for decoding encoded content including a pluralityof encoded frames, comprising: receiving by a processing element theencoded frames, wherein the encoded frames comprise at least one contentframe and at least one null frame; detecting by the processing element asynchronization signal corresponding to the encoded frames; andcompiling by the processing element the encoded frames into aframe-sequential stream of frames according to the detectedsynchronization signal, such that the at least one null frame is notdisplayed when the frame-sequential stream of frames is displayed. 19.The method of claim 18, wherein the synchronization signal is detectedbased on at least one one of the presence of the null frames or acadence of the null frames.
 20. The method of claim 18, wherein theencoded content is one of compressed content, encrypted content, orcompressed and encrypted content.
 21. The method of claim 18, whereinthe content frames comprise left-eye image frames and right-eye imageframes, and wherein the synchronization signal establishes an accuratedisplay order of the left-eye image frames and right-eye image frames.22. The method of claim 18, wherein the receiving further comprisestemporarily storing the encoded stream of frames in a frame buffer. 23.A system comprising: a display device capable of displayingthree-dimensional (3-D) multimedia content; and a decoder configured to:extract an encoded stream of frames having a first image type, a secondimage type, and at least one null image from a 3-D content source;obtain synchronization information from the encoded stream of frames;generate a frame-sequential stream of frames for the first image type,the second image type, and the at least one null image based on thesynchronization information; and transmit the frame-sequential stream offrames to a display device, wherein the display device is configured todiscard the null images when the frame-sequential stream of frames isdisplayed.
 24. The system of claim 23, wherein the first image typecorresponds to one of a left-eye image and a right-eye image, and thesecond image type corresponds to the other of a left-eye image and aright-eye image.
 25. The system of claim 23, wherein the display devicedisplays the frame-sequential stream of frames in the order determinedby the synchronization information.
 26. The system of claim 25, whereinthe synchronization information is obtained based on one of the presenceof the null frames, a cadence of the null frames, or both.
 27. Thesystem of claim 23, wherein the decoder is configured to transmit thestream of video frames at a rate twice that of the original stream ofvideo frames.